Francesca Nardello

Measured and predicted mechanical internal work in human locomotion.

Predictive methods estimating mechanical internal work (W(int), i.e., work to accelerate limbs with respect to BCOM during locomotion) are needed in absence of experimental measurements. A previously proposed model equation predicts such a parameter based upon velocity, stride frequency, duty factor, and a compound critical term (q) accounting for limb geometry and inertial properties. That first predicted W(int) estimate (PW(int)) has been validated only for young males and for a limited number of horses. The present study aimed to extend the comparison between model predictions and experimentally measured W(int) (MW(int)) data on humans with varying gender, age, gait, velocity, and gradient. Seventy healthy subjects (males and females; 7 age groups: 6-65 years) carried out level walking and running on treadmill, at different velocities. Moreover, one of the subject groups (25-35 years) walked and ran also at several uphill/downhill gradients. Reference values of q represent the main important results: (a) males and females have similar q values; (b) q is independent on velocity and gradient. Also, different data filtering depth was found to affect MW(int) and, indirectly, PW(int), thus also the reference q values here obtained (0.08 in level, 0.10 in gradient) suffer a--20% underestimation with respect to the previous predicting model. Despite of this effect, the close match between MW(int) and PW(int) trends indicates that the model equation could be satisfactorily applied, in various locomotion conditions.

Does the Pisa syndrome affect postural control, balance, and gait in patients with Parkinson's disease? An observational cross-sectional study.

INTRODUCTION An altered sense of verticality, associated with impaired proprioception and somatosensory integration deficits, has been reported in patients with Parkinsons disease (PD) but it has not been characterized in patients with Pisa syndrome (PS). Therefore, we investigated postural control, balance, and gait disturbances in patients with PD and PS, patients with PD but without PS, and aged-matched normal controls. METHODS This observational cross-sectional study involved patients with PD and PS (n = 10, Hoehn & Yahr score <4), patients with PD but without PS (n = 10), and age-matched healthy controls (n = 10). The primary outcome measure was the velocity of CoP displacement (VEL_MED_AP/ML) assessed by static stabilometry in eyes open (EO) and eyes closed (EC) conditions. The secondary outcomes were other stabilometric parameters, the Sensory Organization Balance Test (SOT), and gait analysis (GA). RESULTS There were no significant differences in demographic and clinical data and Berg Balance Scale scores between the groups. There was a significant main effect in the VEL_MED_AP/ML between the groups and eye conditions (p = .016). A significant main effect was found in the EO (p = .01) and EC (p = .04) conditions. Post-hoc comparisons showed a significant increase in VEL_CoP in both the EO and EC conditions only in the patients with PD and PS. No significant main effects on SOT and GA were found. CONCLUSION Patients with PD and PS had more difficulty achieving good postural alignment with gravity and greater velocity of body sway than the other groups. Rehabilitation programs for patients with PD and PS should include spine alignment and dynamic postural training.

Anatomically Asymmetrical Runners Move More Asymmetrically at the Same Metabolic Cost

We hypothesized that, as occurring in cars, body structural asymmetries could generate asymmetry in the kinematics/dynamics of locomotion, ending up in a higher metabolic cost of transport, i.e. more ‘fuel’ needed to travel a given distance. Previous studies found the asymmetries in horses’ body negatively correlated with galloping performance. In this investigation, we analyzed anatomical differences between the left and right lower limbs as a whole by performing 3D cross-correlation of Magnetic Resonance Images of 19 male runners, clustered as Untrained Runners, Occasional Runners and Skilled Runners. Running kinematics of their body centre of mass were obtained from the body segments coordinates measured by a 3D motion capture system at incremental running velocities on a treadmill. A recent mathematical procedure quantified the asymmetry of the body centre of mass trajectory between the left and right steps. During the same sessions, runners’ metabolic consumption was measured and the cost of transport was calculated. No correlations were found between anatomical/kinematic variables and the metabolic cost of transport, regardless of the training experience. However, anatomical symmetry significant correlated to the kinematic symmetry, and the most trained subjects showed the highest level of kinematic symmetry during running. Results suggest that despite the significant effects of anatomical asymmetry on kinematics, either those changes are too small to affect economy or some plastic compensation in the locomotor system mitigates the hypothesized change in energy expenditure of running.

Sled Towing: The Optimal Overload for Peak Power Production

PURPOSE The effects of different loads on kinematic and kinetic variables during sled towing were investigated with the aim to identify the optimal overload for this specific sprint training. METHODS Thirteen male sprinters (100-m personal best: 10.91 ± 0.14 s) performed 5 maximal trials over a 20-m distance in the following conditions: unloaded and with loads from 15% to 40% of the athletes body mass (BM). In these calculations the sled mass and friction were taken into account. Contact and flight times, stride length, horizontal hip velocity (vh), and relative angles of hip, knee, and ankle (at touchdown and takeoff) were measured step by step. In addition, the horizontal force (Fh) and power (Ph) and maximal force (Fh0) and power (Ph0) were calculated. RESULTS vh, flight time, and step length decreased while contact time increased with increasing load (P < .001). These variables changed significantly also as a function of the step number (P < .01), except between the 2 last steps. No differences were observed in Fh among loads, but Fh was larger in sled towing than in unloaded. Ph was unaffected by load up to +20%BM but decreased with larger loads. Fh0 and Ph0 were achieved at 20%BM. Up to 20%BM, no significant effects on joint angles were observed at touchdown and takeoff, while at loads >30%BM joint angles tended to decrease. CONCLUSION The 20%BM condition represents the optimal overload for peak power production-at this load sprinters reach their highest power without significant changes in their running technique (eg, joint angles).

A kinematic and metabolic analysis of the first Lu of Tai Chi in experts and beginners.

The aim of this study was to compare movement kinematics, cocontraction times, and metabolic data in expert and nonexpert Tai Chi practitioners. Significant differences were observed for all kinematic parameters: experts moved smoothly (lower jerk) and with a lower frequency. No differences in metabolic and electromyography data were observed but for the breathing pattern (experts breathed slowly and deeply). Movement frequency and breathing pattern are thus the main features that distinguish expert and nonexpert practitioners.

Sprint running: how changes in step frequency affect running mechanics and leg spring behaviour at maximal speed.

ABSTRACT The purpose of this study was to investigate the changes in selected biomechanical variables in 80-m maximal sprint runs while imposing changes in step frequency (SF) and to investigate if these adaptations differ based on gender and training level. A total of 40 athletes (10 elite men and 10 women, 10 intermediate men and 10 women) participated in this study; they were requested to perform 5 trials at maximal running speed (RS): at the self-selected frequency (SFs) and at SF ±15% and ±30%SFs. Contact time (CT) and flight time (FT) as well as step length (SL) decreased with increasing SF, while kvert increased with it. At SFs, kleg was the lowest (a 20% decrease at ±30%SFs), while RS was the largest (a 12% decrease at ±30%SFs). Only small changes (1.5%) in maximal vertical force (Fmax) were observed as a function of SF, but maximum leg spring compression (ΔL) was largest at SFs and decreased by about 25% at ±30%SFs. Significant differences in Fmax, Δy, kleg and kvert were observed as a function of skill and gender (P < 0.001). Our results indicate that RS is optimised at SFs and that, while kvert follows the changes in SF, kleg is lowest at SFs.